Electrolytic heating

ABSTRACT

Heating an electrolytic solution by placing at least three spaced electrodes in direct contact with the solution and connecting two of the electrodes to a source of power to cause electrical current to pass between the two electrodes along a path including the solution and the third electrode.

United States Patent [72} Inventor Milton S. Cohen 41 Scituate St.,Arlington, Mass. 02174 {21] Appl. No. 820,934 [22] Filed May1,1969 [45]Patented Sept. 14, 1971 [54] ELECTROLYTIC HEATING 20 Claims, 3 DrawingFigs.

[52] US. Cl 219/200, 219/293, 219/385 [51] Int. Cl 1105b 1/00 [50] Field01 Search ....2 19/280-286,

[56] References Cited UNlTED STATES PATENTS 421,499 2/1890 Hubinger219/293 1,098,338 5/1914 Thompson 204/146 UX 1,985,623 12/1934 Ross219/288 X 2,655,473 10/1953 Lowenheim... 204/146 X 2,739,] 12 3/1956Ferguson 204/146 X 2,783,355 2/1957 Vassiliev 219/293 3,020,385 2/1962Conlin et al. 219/295 X 3,062,663 1 1/1962 Furgal et a1 99/174 X3,483,358 12/1969 Eisler 219/385 2,879,367 3/1959 McLean 219/385 PrimaryExaminer.l. V. Truhe Assistant ExaminerC. L. Albritton Attorney-W. R.Hulbert ABSTRACT: Heating an electrolytic solution by placing at leastthree spaced electrodes in direct contact with the solution-andconnecting two of the electrodes to a source of power to causeelectrical current to pass between the two electrodes along a pathincluding the solution and the third electrode.

PATENTED SEP 1 4 |97l ELECTROLYTIC HEATING This invention relates toelectrolytic heating.

It is a primary object of the present invention to provide a method andapparatus for decreasing the time required to heat an electrolyticsolution to a desired temperature condition without increasing the sizeor number of electrodes connected directly to a current source. Otherobjects include providing such a method and apparatus in which, withoutchange in or adjustment to the current source, high current is initiallypassed through the solution to heat it to a desired temperaturecondition and the current level is then automatically decreased to thatrequired to maintain the solution at the desired condition.

The invention features, in one aspect, a pair of spaced primaryelectrodes adapted for connection to a source of electrical powerand atleast one secondaryelectrode, the primary and secondary electrodes beingadapted for directly contactingan electrolytic solution and the solutionproviding the sole electrical connection between the primary electrodesand the secondary electrodes. In preferred embodiments, this aspect ofthe invention features a plurality of secondary electrodes each of whichare of material of higher negative electromotive potential and ofsubstantially less thickness than the primary electrodes and which areeroded by the passage of electrical current through the solution. Inanother aspect, the invention features heating an electrolytic solutionby placing at least three spaced electrodes in direct contact with thesolution and connecting two of the electrodes to a source of power tocause electrical current to pass between the two electrodes along a pathincluding the solution and the third electrode. Preferred embodiments ofthis aspect of the invention further feature effectively withdrawing thethird electrode from the solution after the solution has been heated toa desired condition, automatically decreasing the level of currentpassing through the solution.

Other objects, features and advantages will become apparent from thefollowing detailed description of a preferred embodiment of theinvention, taken together with the attached drawings, in which:

FIG. 1 is a perspective view, partially in section, of a food packageembodying the electrolyte heating system present invention;

FIG. 2 is a perspective view of the heating assembly of the food packageof FIG. 1; and,

FIG. 3 is a perspective view of a box blank used in the food package ofFIG. 1.

Referring more particularly to the drawings there is shown a foodpackage, indicated generally at 10, including a container comprising anouter sheet 12 of 200-lb.-test corrugated paperboard folded into a boxof 8 inches by 10 inches by 2 inches interior dimensions, a standard (9inch by 7 inch) frozen-dinnersize food tray 16 enclosed in a sealedelectrically insulating polyethylene sheet 18, an electricallyinsulating polyethylene sheet 14, 0.002 inch thick and (with trimmedcomers) 1 yard square, gathered about all internal parts of the package,including food tray 16, and defining the interior surface of thecontainer, and a pair of identical Winch-high spacers 20, 22, each madeof a network of interconnected strips of paperboard having flowcommunicating openings 23 therethrough, disposed between polyethylenesheets 14 and 18, respectively, above and below food tray 16.

Referring to FIGS. 1 and 3, box blank 12 (which provides structuralstrength and c insulation for the package during both storage andheating) includes a bottom panel 30, a first pair of side panels 32secured to opposite transverse edges of bottom panel 30 along fold lines31, and a third side panel 34 secured to a longitudinal edge of bottompanel 30 along a fold line 33 perpendicular to fold lines 31. Aninterior top half panel 36 is secured to each of side panels 32 along afold line 35 parallel to fold lines 31. The portion of each half panel36 opposite its fold line 35 includes a semicircular notch 38 whichcooperates with the notch 38 on the other top half panel upon folding ofthe blank (FIG. 1) to form a IVz-inchdiameter opening 38a. An exteriortop panel 40 secured to side panel 34 along a fold line 39 includes aprecut 3-inch in diameter circular portion 42 which is removed when thepackage is to be heated to expose a circular opening 42a. A fourth sidepanel 44 is secured to the edge of top panel 40 opposite side panel 34along fold line 43 and a closure flap 46 is secured to side panel 44along fold line 45 parallel to fold lines 33 and 39. A precut U-shapedtab 47 isprovided in panel 44 and a pair of T-shaped slots 48 areprovided in closure flap 46. The crossbar of each slot is parallel to,and the leg of each slot is perpendicular to and intersects thetransverse free edge 50 of flap 46. Support flaps 52 are connected toside panels 32 along fold lines 53 and support flaps 56 are connected toside panel 34 along fold lines 57.

A sheet 58 of textured-paper towel is provided on top of bottom panel 30to provide heat insulation and also to protect polyethylene sheet 14from wear by abrasion.

When box blank 12 is folded into a food package (as in FIG. I), thegathered portion 15 of polyethylene sheet 14 extends through opening 38aand is turned back around the opening and sealed to the top of interiorhalf-panels 36 between interior panels 36 and exterior panel 40 byScotch brand Sand Blast Filler Type 02, manufactured by Minnesota Mining& Mfg. Co., precoated onto the top of half-panels 36.

Referring now to FIG. 2, a pair of primary electrodes 62 (tinned steelstrip 0.01 inch thick and three-quarters inch wide) and four secondaryelectrodes 63 (aluminum strip 0.001 inch thick, 1%inches wide, and 5inches long) are heatbonded with a thermoplastic adhesive to aninsulating sheet 60 (paperboard 9 inches long and 7 inches wide) inparallel spaced-apart relationship with secondary electrodes 63 betweenprimary electrodes 62. The space between adjacent secondary electrodes63 is one-eighth inch; that between each primary electrode 62 and theadjacent secondary electrode 63 is one-fourth inch.

The entire length of each secondary electrode 63 is heat sealed to sheet60. Each primary electrode 62 includes an inner portion (Including ahorizontal section 66 bonded to sheet 60 and a vertical section 68extending upwardly from sheet 60) within the enclosure formed byflexible sheet 14 and an outer portion 64 without sheet 14. A dimple 69in vertical section 68 extends through a mating hole in sheet 14 intocontact with a vertical section of outer portion 64. The two verticalsections are spot welded together at the dimple to provide electricalconnection therebetween and a watertight seal through the sheet.

For connection to a source of electrical power, the outer portion 64 ofeach primary electrode includes a substantially U-shaped horizontalfemale connector 72 connected to the vertical section of the outerportion at right-angle bend 71. The tinned strip forming the lowerportion of connector 72 is curved and includes, at its free end, adownwardly facing pointed tip 76.

When the food package is assembled, the outer portion 64 of each primaryelectrode 62 extends through the crossbar of one of the T-slots 48 inclosure flap 46 (bend 71 engaging the slot), and connector 72 liesbetween closure flap 46 and bottom panel 30 with pointed tip 76 digginginto the interior surface of bottom panel 30.

Deposits 80 (totaling 6 grams) of salt (Fine Prepared Flour Salt sold bythe Diamond Crystal Salt Co.) are dispersed on insulating sheet 60 inall the spaces between adjacent pairs of electrodes 62 and 63. A sheet82 of textured paper towel overlies the deposits to retain them in placebetween the electrodes.

In operation, to heat and, as required cook, the frozen food containedin food tray 16, circular portion 42 of exterior top panel 40 isremoved, exposing opening 42a, about 8 ounces of water is introducedinto the cavity formed by sheet 14 (through openings 42a and 38a),flowing over and around the polyethylene sheet 18 surrounding tray 16onto insulating sheet 60. The water fills the cavity defined bypolyethylene sheet 14 to a level just below the bottom of food tray 16and dissolves salt 80 thereby forming a conductive aqueous orelectrolytic solution. Sheet 14, with spacer 22, forms a pan for theconductive liquid and the openings 23 is spacer 22 permit flow of liquidhorizontally therethrough to insure a substantially even liquid level.Primary electrodes 62 are then connected to an AC source (typicallyll-l20-volt, 60-cycle house current), causing current to flow throughand heat to boiling the conductive aqueous solution. The steam thusproduced surrounds, heats, and, as required, cooks the food in tray 16.Most of the steam, after performing some heating, condenses on the sheet18 surrounding food tray 16 and on the top inside portion of sheet 14and is returned as condensate to the boiling liquid pool below the foodtray and between the electrodes. Some steam continually escapes throughvent 380. When enough water from the conductive solution has escaped (assteam), current flow through the solution rapidly decreases and finallystops altogether.

In practice, the cooking cycle includes an initial period of about 1minute during which a high current (approximately 7-8 amps) is passedthrough the solution to rapidly heat it to boiling, a cooking period ofl2-to 16-minutes duration during which a lower current (typically about3 amps) is passed through the solution to cause it to continue to boilat a substantially constant rate, and a cutofi period during which bothcurrent flow and rate of boiling rapidly decrease. The cutoff period maybe as long as minutes if the water is permitted to boil off to the pointwhere current flow completely ceases, but is generally shortened bydisconnecting the package from the power source when, as shown bysubstantial decrease in the amount of steam from vent 38a, the currentflow and cycle have entered the cutoff region.

During the initial period, high current is desired for rapidly heatingthe conductive solution to boiling. During the cooking period, a farlower current level is required simply to maintain the solution boilingbut at a relatively low level so that the rate of water loss is notexcessive. The current level during the cooking period depends onconductivity of the primary electrodes and conductive solution. Thehigher initial period current is provided by secondary electrodes 63.

During the initial period, current passes between principal electrodes62 along a relatively low-resistance path including both the conductivesolution and secondary electrodes 63. This high initial period currentrapidly erodes away the secondary electrodes (which are very thin and ofmaterial having a higher negative electromotive potential than does thematerial of the primary electrodes) so that, by the end of the initialperiod, only a small portion (approximately one-fourth to onehalf inchwide and indicated by the dashed outlines in FIG. 2) of each secondaryelectrode 63 remains. This erosion process effectively removes thesecondary electrodes from the current path so that, during the cookingperiod, current must pass between primary electrodes along the higherresistance path extending almost entirely through the conductivesolution. Thus, without any change whatever in the electric power sourceconnected to the package, two different current levels, each at thedesired time, are provided.

Other embodiments within the scope of the following claims will occur tothose skilled in the art.

What is claimed is:

l. The method of heating an electrolytic solution comprising the stepsof:

placing at least three relatively spaced electrodes in direct contactwith said solution;

connecting at least two of said electrodes to a source of electricalpower;

passing electrical current between said two electrodes connected to saidsource along a path including said solution and at least one electrodewhich is not connected to said source;

effectively removing said one electrode which is not connected to saidsource from said path after said solution has been heated to a desiredextent; and,

thereafter continuing to pass electrical current between said twoelectrodes which are connected to said source. 2. The method of claim 1including the step of effectively removing said one electrode by aprocess of erosion. 5 3. The method of claim 2 wherein said oneelectrode is of a material having a higher negative electromotivepotential than the material of another of said electrodes.

4. The method of heating an electrolytic solution comprising the stepsof:

placing at least three relatively spaced electrodes in direct contactwith said solution so that the resistance between two of said electrodesalong a first path including said solution and the third of saidelectrodes is substantially less than is the resistance between said twoelectrodes along a second path including said solution but not includingsaid third electrode;

connecting said two electrodes to a source of electrical power;

passing electrical current between said two electrodes along said firstpath, said third electrode not being connected to said source;

effectively removing said third electrode from said path after saidsolution has been heated to a desired extent; and,

thereafter continuing to pass electrical current between said twoelectrodes.

5. The method of claim 4 wherein said one electrode is of substantiallyless thickness than are said two electrodes and is effectively removedfrom said path by a process of erosion.

' 6. The method of claim 5 wherein said one electrode is of materialhaving a higher negative electromotive potential than the material ofsaid two electrodes.

7. ln apparatus for heating an electrolytic solution and including apair of relatively spaced, longitudinally extending primary electrodesadapted for direct electrical connection to a source of power and atleast one secondary electrode spaced from and electrically insulatedfrom said primary electrodes whereby said secondary electrode is adaptedfor electrical connection to said primary electrodes and said source ofpower solely through a solution, that improvement wherein:

said secondary electrode has a first dimension measured in a directiongenerally parallel to the direction of longitudinal extent of saidprimary electrodes,

a second dimension measured in a direction generally parallel to a lineextending between said primary electrodes, and

a third dimension measured in a direction generally perpendicular tosaid line and said direction of longitudinal extent, each of said firstand second dimensions being substantially greater than said thirddimension,

whereby when said electrodes are immersed in an electrolytic solutionthe resistance between said primary electrodes along a first pathincluding said solution and said secondary electrode is substantiallyless than the resistance between said primary electrodes along a secondpath including said solution but not including said secondary electrode;and,

said secondary electrode is effectively self-removable from said firstpath in response to the passage of current along said first path.

8. The apparatus of claim 7 wherein said secondary electrode is ofmaterial having greater negative electromotive potential than thematerial of at least one of said primary electrodes.

9. The apparatus of claim 7 wherein said secondary electrode is of lessthickness than are said primary electrodes.

10. The apparatus of claim 9 wherein said secondary electrode isaluminum and said primary electrodes are steel.

11. An apparatus for heating an electrolytic solution comprising theapparatus of claim 7 in further combination with:

a container whose inner surface defines an interior cavity;

and,

a food compartment disposed within said cavity,

said electrodes being mounted within said cavity below and spaced fromsaid food compartment.

12. The apparatus of claim 11 wherein said secondary electrode is of amaterial having greater negative electromotive potential than thematerial of said primary electrodes.

13. The apparatus of claim 11 wherein the thickness of said secondaryelectrode is not more than one-half the thickness of said primaryelectrodes.

14. The apparatus of claim 13 wherein said primary electrodes are steeland said secondary electrode is aluminum.

15. The apparatus of claim 11 including a sheet of electricallynonconductive material disposed within said cavity, and a plurality ofrelatively spaced secondary electrodes disposed intermediate saidprimary electrodes, said electrodes being secured to said sheet inparallel spaced-apart relationship and each of said secondary electrodesbeing of lesser thickness than, and of material of higher negativeelectromotive potential than the material of said primary electrodes.

16. The apparatus of claim 11 wherein said electrodes are secured, inparallel spaced-apart relationship, to a sheet of electricallynonconductive material disposed within said cavity and includingdeposits of an electrolyte disposed on said sheet intermediate adjacentpairs of said electrodes.

17. The apparatus of claim 16 wherein said electrolyte is salt.

18. The apparatus of claim 17 including a water-pervious sheet overlyingsaid deposits for maintaining said deposits in position intermediatesaid electrodes.

19. The method of claim 4 wherein said electrodes are substantiallyparallel to each other, said third electrode is substantiallyrectangular in transverse cross section, and said third electrode ispositioned with the major transverse dimension thereof substantiallyparallel to a line between said two electrodes.

20. The apparatus of claim 7 wherein said electrodes extend indirections substantially parallel to each other and said secondaryelectrode is substantially rectangular in transverse cross section.

UNETED STATES PATENT OFFICE CERTWICATE OF (IORRECTION Patent No. 6 4 8gDated September 1 1, 1971 Inventor(s) Milton Saul Cohen It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 67, the letter "c" should be -thermal-;

Column 2, line 41, the word "(Including...)"

should be --(including.

Signed and sealed this 2nd day of May 1972.

EDWARD MeFLETfiHffi, JR.

ROBERT GOTTSCHALK Attesting Officer Co missioner of Patents M PO-IOSOH0459] USCOMM-DC 6O376-PB9 u s GOVERNMENY PRlNTiNG OFFICE we! o3ss-334

2. The method of claim 1 including the step of effectively removing said one electrode by a process of erosion.
 3. The method of claim 2 wherein said one electrode is of a material having a higher negative electromotive potential than the material of another of said electrodes.
 4. The method of heating an electrolytic solution comprising the steps of: placing at least three relatively spaced electrodes in direct contact with said solution so that the resistance between two of said electrodes along a first path including said solution and the third of said electrodes is substantially less than is the resistance between said two electrodes along a second path including said solution but not including said third electrode; connecting said two electrodes to a source of electrical power; passing electrical current between said two electrodes along said first path, said third electrode not being connected to said source; effectively removing said third electrode from said path after said solution has been heated to a desired extent; and, thereafter continuing to pass electrical current between said two electrodes.
 5. The method of claim 4 wherein said one electrode is of substantially less thickness than are said two electrodes and is effectively removed from said path by a process of erosion.
 6. The method of claim 5 wherein said one electrode is of material having a higher negative electromotive potential than the material of said two electrodes.
 7. In apparatus for heating an electrolytic solution and including a pair of relatively spaced, longitudinally extending primary electrodes adapted for direct electrical connection to a source of power and at least one secondary electrode spaced from and electrically insulated from said primary electrodes whereby said secondary electrode is adapted for electrical connection to said primary electrodes and said source of power solely through a solution, that improvement wherein: said secondary electrode has a first dimension measured in a direction generally parallel to the direction of longitudinal extent of said primary electrodes, a second dimension measured in a direction generally parallel to a line extending between said primary electrodes, and a third dimenSion measured in a direction generally perpendicular to said line and said direction of longitudinal extent, each of said first and second dimensions being substantially greater than said third dimension, whereby when said electrodes are immersed in an electrolytic solution the resistance between said primary electrodes along a first path including said solution and said secondary electrode is substantially less than the resistance between said primary electrodes along a second path including said solution but not including said secondary electrode; and, said secondary electrode is effectively self-removable from said first path in response to the passage of current along said first path.
 8. The apparatus of claim 7 wherein said secondary electrode is of material having greater negative electromotive potential than the material of at least one of said primary electrodes.
 9. The apparatus of claim 7 wherein said secondary electrode is of less thickness than are said primary electrodes.
 10. The apparatus of claim 9 wherein said secondary electrode is aluminum and said primary electrodes are steel.
 11. An apparatus for heating an electrolytic solution comprising the apparatus of claim 7 in further combination with: a container whose inner surface defines an interior cavity; and, a food compartment disposed within said cavity, said electrodes being mounted within said cavity below and spaced from said food compartment.
 12. The apparatus of claim 11 wherein said secondary electrode is of a material having greater negative electromotive potential than the material of said primary electrodes.
 13. The apparatus of claim 11 wherein the thickness of said secondary electrode is not more than one-half the thickness of said primary electrodes.
 14. The apparatus of claim 13 wherein said primary electrodes are steel and said secondary electrode is aluminum.
 15. The apparatus of claim 11 including a sheet of electrically nonconductive material disposed within said cavity, and a plurality of relatively spaced secondary electrodes disposed intermediate said primary electrodes, said electrodes being secured to said sheet in parallel spaced-apart relationship and each of said secondary electrodes being of lesser thickness than, and of material of higher negative electromotive potential than the material of said primary electrodes.
 16. The apparatus of claim 11 wherein said electrodes are secured, in parallel spaced-apart relationship, to a sheet of electrically nonconductive material disposed within said cavity and including deposits of an electrolyte disposed on said sheet intermediate adjacent pairs of said electrodes.
 17. The apparatus of claim 16 wherein said electrolyte is salt.
 18. The apparatus of claim 17 including a water-pervious sheet overlying said deposits for maintaining said deposits in position intermediate said electrodes.
 19. The method of claim 4 wherein said electrodes are substantially parallel to each other, said third electrode is substantially rectangular in transverse cross section, and said third electrode is positioned with the major transverse dimension thereof substantially parallel to a line between said two electrodes.
 20. The apparatus of claim 7 wherein said electrodes extend in directions substantially parallel to each other and said secondary electrode is substantially rectangular in transverse cross section. 